Turbocharged and supercharged engines may be configured to compress ambient air entering the engine in order to increase power. Because compression of the air may cause an increase in air temperature, a charge air cooler may be utilized to cool the heated air thereby increasing its density and further increasing the potential power of the engine. If the humidity of the ambient air is high, however, condensation (e.g., water droplets) may form on any internal surface of the charge air cooler that is cooler than the dew point of the compressed air. During transient conditions such as hard vehicle acceleration, these water droplets may be blown out of the charge air cooler and into the combustion chambers of the engine resulting in increased potential for engine misfire, loss of torque and engine speed, and incomplete combustion, for example.
One approach for reducing the amount of condensation entering the combustion chambers is disclosed in US Patent Application Publication 2011/0094219 A1. In the cited reference, a condensation trap for a charge air cooler that reduces the rate at which condensation enters the combustion chambers of the engine is disclosed. The condensation trap includes a reservoir for collecting the condensate and a tube for releasing the condensate back to the outlet duct.
The inventors herein have recognized various issues with the above system. In particular, the condensation trap is positioned downstream of the charge air cooler and thus can only collect condensation downstream from an outlet of the charge air cooler. This configuration may not adequately address condensation trapped within the charge air cooler. Furthermore, condensation traps necessitate additional componentry that may increase the cost and the packaging space of the charge air cooler.
As such, one example approach to address the above issues includes an engine cooling system, comprising a charge air cooler having an inlet, a plurality of heat exchange passages fluidically coupled to the inlet, and an outlet fluidically coupled to the heat exchange passages, and a conduit coupled to the outlet and an intake manifold of an engine, the conduit divided to include a first and second flow path to the intake manifold with a valve positioned in the first flow path.
By providing a conduit having two flow paths, the velocity of the intake air as it exits the charge air cooler may be modulated. In one example, the valve may be configured to be closed during lower intake velocity conditions, such as low load. The closed valve may block the inlet of the first flow path, thus resulting in the intake air flowing only through the second flow path. In doing so, the velocity of the intake air increases and accumulated condensate in the charge air cooler may be entrained in the intake air and moved to the intake manifold. This may reduce the accumulation of large amounts of condensate. As engines may be able to tolerate small amounts of condensate within the intake air without misfiring, the approach described above provides a mechanism for passing small amounts of condensate to the engine and reduces the likelihood of engine misfire due to large amounts of condensate reaching the engine.
As the closed valve blocks part of the flow path of the conduit, it also increases the pressure drop across the outlet of the charge air cooler. To prevent a large pressure drop that may occur during high velocity conditions (and that may result in inefficient engine air flow), the valve may open during high intake air velocity conditions. During high intake air velocity conditions, the intake air is already traveling with increased velocity, and the velocity of the intake air need not be further increased in order to entrain the condensate within the intake air. Thus, when the valve is both open and closed, accumulated condensate may be moved to the engine.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.